HMMT 二月 2000 · POW 赛 · 第 10 题
HMMT February 2000 — POW Round — Problem 10
题目详情
- Find the n um b er of distributions of a giv en set of m iden ti al balls in to a giv en set of n distin t b o xes.
解析
- or . This an b e seen from the fa t that ea h distribution an b e m n 1 des rib ed b y a om bination of letters, where ea h letter represen ts a di eren t b o x. The n um b er of times ea h letter o urs in the om bination is determined b y the n um b er of balls in the orresp onding b o x. m ! m m m m m m 1 1 2